Stool seat shell



FIG. 1 is a front isometric view of the stool seat shell incorporating my new design;

FIG. 2 is a right side elevation view thereof, wherein the left side elevation view is a mirror image thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The portions shown in broken lines illustrate environment only and form no part of the claimed design. 

CLAIM The ornamental design for a stool seat shell, as shown and described. 